1. Field
Exemplary embodiments of the present invention relate to a liquid crystal display.
2. Discussion of the Background
Liquid crystal displays (LCDs) are one of the most widely used flat panel is displays, and an LCD includes a pair of panels provided with field-generating electrodes, such as pixel electrodes and a common electrode, and a liquid crystal (LC) layer disposed between the two panels. The LCD displays images when voltages are applied to the field-generating electrodes to generate an electric field in the LC layer that determines the orientations of LC molecules therein to adjust polarization of incident light.
In a vertical alignment (VA) mode LCD, the longitudinal axes of the LC molecules are perpendicular to the upper and lower panels in the absence of an electric field, and thus, the contrast ratio may be large and the reference viewing angle may be wide.
In the VA mode LCD, to obtain a wide viewing angle a plurality of domains in which the alignment directions of the LC molecules are different from each other may be formed in one pixel.
To achieve this, at least one cutout may be formed in at least one field generating electrode. In this method, the plurality of domains may be formed by aligning the LC molecules vertically with respect to the fringe field generated between the edges of the cutout and the field generating electrodes facing the edges.
However, the aperture ratio may be decreased in this structure. Also, the LC molecules disposed near the cutouts may be easily aligned vertically with respect to the fringe field, but the LC molecules disposed in the central portions of the domains, which are far from the cutouts, may generate a random motion such that the response speed becomes slow. Moreover, a domain of the reverse direction may be formed, thereby causing an instant afterimage to appear.
Alternatively, the alignment direction of the LC molecules and the alignment angle may be controlled by irradiating light onto the alignment layer. In this light alignment method, it may not be necessary to form the cutouts in the field generating electrodes so the aperture ratio may be increased and the response time of the LC molecules may be improved by a pre-tilt angle generated during the light alignment.
On the other hand, the VA mode LCD may have lower side visibility than front visibility, and, to solve this problem, one pixel may be divided into two sub-pixels, and different voltages be applied to the sub-pixels.
However, when the light alignment method is adapted to a structure having two sub-pixels, the alignment direction of LC molecules subjected to the light alignment may be different from the alignment direction of the LC molecules generated by the fringe field in a gap between two sub-pixels of the LCD so that texture may be generated in the corresponding portion. The texture may decrease transmittance and appear as a stain such that the display characteristics may be deteriorated.